U.S. patent number 6,234,870 [Application Number 09/382,109] was granted by the patent office on 2001-05-22 for serial intelligent electro-chemical-mechanical wafer processor.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Daniel C. Edelstein, Cyprian E. Uzoh.
United States Patent |
6,234,870 |
Uzoh , et al. |
May 22, 2001 |
Serial intelligent electro-chemical-mechanical wafer processor
Abstract
An apparatus for removing material from a substrate including a
plurality of polishing cells. A first polishing cell detects the
material on the substrate and performs a first polishing operation
for removing material from the substrate. The first polishing cell
includes at least one sensor for characterizing the material on the
substrate and at least one polishing tool for removing material
from the substrate. A second polishing cell includes at least one
polishing tool for completing the polishing process.
Inventors: |
Uzoh; Cyprian E. (Milpitas,
CA), Edelstein; Daniel C. (New Rochelle, NY) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
|
Family
ID: |
23507558 |
Appl.
No.: |
09/382,109 |
Filed: |
August 24, 1999 |
Current U.S.
Class: |
451/8; 451/285;
451/287; 451/288; 451/289; 451/41; 451/5 |
Current CPC
Class: |
B23H
5/08 (20130101); B24B 27/0076 (20130101); B24B
37/046 (20130101); B24B 37/345 (20130101); B24B
49/04 (20130101) |
Current International
Class: |
B24B
27/00 (20060101); B24B 49/04 (20060101); B24B
49/02 (20060101); B24B 37/04 (20060101); B04B
001/00 () |
Field of
Search: |
;451/5,8,41,285,287,288,289 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hail, III; Joseph J.
Assistant Examiner: McDonald; Shantese
Attorney, Agent or Firm: Connolly, Bove, Lodge & Hutz
Abate, Esquire.; Joseph P.
Claims
I claim:
1. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the first polishing cell further comprises a processor for
determining composition of a first polishing slurry; and
wherein the first polishing cell comprises three polishing tools
mounted on a rotating turret.
2. The apparatus according to claim 1, wherein the polishing tools
include a high speed electropolishing head, a high rate polishing
head, and a variable pressure head.
3. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the material on the substrate to be removed is at least one
metal or alloy and the first polishing cell polishes the at least
one metal or alloy to within the vicinity of a barrier layer.
4. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the first polishing station comprises an electroetching
head comprising at least one segmented cathode.
5. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the at least one polishing tool of the first polishing cell
comprises a plurality of polishing heads comprising a plurality of
polishing pads.
6. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the first polishing cell further comprises means for
introducing at least one of at least one polishing slurry for
polishing the substrate and deionized water; and
wherein the first polishing cell further comprises at least one
injector for introducing at least one of oxygen, carbon dioxide,
and nitrogen into the at least one polishing slurry.
7. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the second polishing cell further comprises at least one
pattern comparer for comparing a pattern of the material exposed by
the polishing with a known pattern.
8. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
further comprising a recovery loop for recovering material removed
from the substrate.
9. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the second polishing cell further comprises a mapping
inspection station including a dynamic feedback loop.
10. The apparatus according to claim 9, wherein the inspection
station comprises a diode array for scanning a surface of the
substrate recording coordinates on the substrate of locations with
metal residues.
11. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the second polishing cell further comprises at least one
brush tool.
12. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein the second polishing cell further comprises at least one
polishing head comprising at least one polishing pad for locally
removing material from the substrate; and
wherein the second polishing cell comprises a turret and four
polishing heads arranged on the turret, the four polishing heads
including a high rate polishing head, an intermediate rate
polishing head, a touch up finishing head and a polishing head
sufficiently small to permit localized polishing of the
substrate.
13. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
and said apparatus further comprising:
an in situ slurry formulator for formulating slurries based upon
material removal rates.
14. The apparatus according to claim 13, wherein the slurries are
formulated from three master batches.
15. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
and said apparatus further comprising a slurry heater for
controlling temperature of polishing slurries for optimally
polishing the substrate.
16. The apparatus according to claim 15, wherein the heater is an
infrared heater.
17. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
and said apparatus further comprising a slurry chiller for
controlling temperature of polishing slurries for polishing the
substrate.
18. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
and said apparatus further comprising a slurry chiller for
controlling temperature of polishing slurries for polishing surface
cleaning and passivation of the substrate;
wherein the first polishing cell further comprises means for
introducing at least one of at least one polishing slurry for
polishing the substrate and deionized water; and
wherein the first polishing cell further comprises at least one
injector for introducing at least one of oxygen, carbon dioxide,
and nitrogen into the at least one polishing slurry.
19. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the
substrate;
a second polishing cell comprising at least one polishing tool for
completing the polishing process; and
a third polishing cell comprising at least one cleaner for cleaning
the substrate;
wherein the third polishing cell carries out at least one of slurry
removal and metal passivation treatment.
20. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the
substrate;
a second polishing cell comprising at least one polishing tool for
completing the polishing process; and
a third polishing cell comprising at least one cleaner for cleaning
the substrate; and
wherein the third polishing cell further comprises a scanning laser
holography tool for detecting an end point to the cleaning.
21. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the
substrate;
a second polishing cell comprising at least one polishing tool for
completing the polishing process; and
a third polishing cell comprising at least one cleaner for cleaning
the substrate; and
wherein the third polishing cell comprises three brush
cleaners.
22. An apparatus for removing material from a substrate,
comprising:
a plurality of polishing cells comprising:
a first polishing cell for detecting the material on the substrate
and performing a first polishing operation for removing material
from the substrate, the first polishing cell comprising at least
one sensor for characterizing the material on the substrate and at
least one polishing tool for removing material from the substrate;
and
a second polishing cell comprising at least one polishing tool for
completing the polishing process;
wherein at least one of the polishing cells comprises a polishing
head that includes at least one edge electroetching element for
electroetching an edge portion of the substrate.
23. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation; and
completing the polishing operation;
wherein the first polishing cell is carried out with at least one
of three polishing tools mounted on a rotating turret in the first
polishing cell, the three polishing tools including a high speed
electropolishing head, a high rate polishing head, and a variable
pressure head.
24. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation; and
completing the polishing operation;
wherein the material on the substrate to be removed comprises at
least one metal or alloy and the first polishing operation polishes
the at least one metal or alloy to within the vicinity of a barrier
layer.
25. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation;
determining a composition of the at least one polishing slurry for
removing the material from the substrate; and
introducing at least one of oxygen, carbon dioxide, and nitrogen
into the at least one polishing slurry.
26. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
comparing a pattern of the material exposed by the polishing to a
known pattern with at least one pattern comparer included in the
second polishing.
27. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
recovering material removed from the substrate with a recovery
loop.
28. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
inspecting the material and the substrate with a mapping inspection
station including a dynamic feedback loop included in the second
polishing cell.
29. The method according to claim 28, wherein inspecting the
substrate and the material includes scanning a surface of the
substrate with a diode array included in the inspection station and
recording coordinates on the substrate of locations with metal
residues.
30. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
locally removing material from the substrate with at least one
polishing head comprising at least one polishing pad included in
the second polishing cell;
wherein completion of the polishing operation is carried out with
second polishing cell comprising a turret and four polishing heads
arranged on the turret, the four polishing heads including a high
rate polishing head, an intermediate rate polishing head, a touch
up finishing head and a polishing head sufficiently small to permit
localized polishing of the substrate.
31. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
formulating slurries in situ based upon material removal rates.
32. The method according to claim 31, wherein the slurries are
formulated from three master batches.
33. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
heating the at least one polishing slurry with a slurry heater for
controlling temperature of the at least one polishing slurry for
optimally polishing the substrate.
34. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
controlling temperature of the at least one polishing slurry with a
slurry chiller.
35. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation;
wherein the apparatus further comprises a third polishing cell
comprising at least one cleaner for cleaning the substrate; and
carrying out at least one of slurry removal and metal passivation
treatment with the third polishing cell.
36. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing operation;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation;
wherein the apparatus further comprises a third polishing cell
comprising at least one cleaner for cleaning the substrate; and
detecting an end point to the cleaning with a scanning laser
holography tool included in the third polishing cell.
37. A method of removing material from a substrate, comprising:
arranging the substrate on an apparatus comprising a plurality of
polishing cells including a first polishing cell for detecting the
material on the substrate and performing a first polishing
operation for removing material from the substrate, the first
polishing cell comprising at least one sensor for characterizing
the material on the substrate, and at least one polishing tool and
at least one polishing slurry for removing material from the
substrate and a second polishing cell comprising at least one
polishing tool for completing the polishing process;
detecting the material on the substrate;
performing a first polishing operation;
completing the polishing operation; and
electroetching an edge portion of the substrate with a polishing
head that includes at least one edge electroetching element
included in at least one of the polishing cells.
Description
FIELD OF THE INVENTION
The invention relates to a device and method for removing material
from a substrate. In particular, the invention relates to a method
and apparatus for carrying out electrochemical and chemical
mechanical polishing.
BACKGROUND OF THE INVENTION
In a variety of applications, particularly semiconductor device
manufacture process, material needs to be removed from a substrate
or other workpiece. First, material may be deposited on a substrate
or workpiece. Portions of the material may then be removed.
Sometimes, the material may be removed as part of the normal
process. Other times, material may be removed because it is
undesirably deposited in certain locations.
Along these lines, in damascene chip wiring methods, typically
material is deposited over all surfaces on a substrate. A portion
of the material is then removed by polishing to leave material in
desired locations. Among the various processes involved in
damascene chip wiring methods, apart from the photolithography
step, the chemical mechanical polishing step is typically the next
most expensive step.
Typical chemical mechanical polishing apparatuses have a low
throughput. This contributes to the comparatively higher cost of
chemical mechanical polishing.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for removing material
from a substrate. The apparatus includes a plurality of polishing
cells. The polishing cells include a first polishing cell for
detecting the material in a substrate and performing a first
polishing operation for removing material from the substrate. The
first polishing cell includes at least one sensor for
characterizing the material in a substrate and at least one
polishing tool for removing material from the substrate. A second
polishing cell includes at least one polishing tool for completing
the polishing process.
The present invention also provides a method of removing material
from a substrate. The method includes arranging the substrate on an
apparatus including a plurality of polishing cells. The polishing
cells include a first polishing cell for detecting the material in
a substrate and performing a first polishing operation for removing
material from the substrate. The first polishing cell includes at
least one sensor for characterizing the material in a substrate and
at least one polishing tool for removing material from the
substrate. A second polishing cell includes at least one polishing
tool for completing the polishing process. The method also includes
detecting the material on a substrate, performing a first polishing
operation, and completing the polishing operation.
Furthermore, the present invention provides an apparatus for
removing material from a substrate. The apparatus includes at least
one polishing station comprising a plurality of elements for
varying polishing process parameters.
Still other objects and advantages of the present invention will
become readily apparent by those skilled in the art from the
following detailed description, wherein it is shown and described
only the preferred embodiments of the invention, simply by way of
illustration of the best mode contemplated of carrying out the
invention. As will be realized, the invention is capable of other
and different embodiments, and its several details are capable of
modifications in various obvious respects, without departing from
the invention. Accordingly, the drawings and description are to be
regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned objects and advantages of the present invention
will be more clearly understood when considered in conjunction with
the accompanying drawings, in which:
FIG. 1a represents a cross-sectional view of a damascene structure
prior to chemical mechanical polishing;
FIG. 1b represents a cross-sectional view of the structure
illustrated in FIG. 1a after chemical mechanical polishing;
FIG. 2 represents an overhead view of a typical known single wafer
chemical mechanical polishing apparatus;
FIG. 3 represents a cross-sectional view of the apparatus
illustrated in FIG. 2;
FIG. 4 represents an overhead view of a known design of a
multi-wafer chemical mechanical polishing apparatus;
FIG. 5 illustrates an embodiment of a chemical mechanical polishing
apparatus according to the present invention;
FIG. 6a represents a cross-sectional view of a portion of the
apparatus illustrated in FIG. 5 for carrying out at least chemical
mechanical polishing and electroetching of a substrate;
FIG. 6b represents an view of a portion of the embodiment of the
apparatus illustrated in FIG. 6a;
FIG. 6c represents a perspective and cross-sectional view of a
portion of an embodiment of a cathode assembly that may be included
in the apparatus illustrated in FIGS. 6a and 6b;
FIG. 6d represents a cross-sectional view of a portion of an
embodiment of a polishing head according to the present invention
that may be included in the apparatus illustrated in FIGS.
6a-6c;
FIG. 7 represents another embodiment of an apparatus for chemical
mechanical polishing and electro etching according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1a illustrates an example of a damascene structure. The
structure in FIG. 1a includes a substrate 1. Dielectric material 3
typically has been deposited and patterned on the substrate 1. An
electrically conductive material 5 typically is deposited in and on
the dielectric layer 3. After depositing the electrically
conductive material 5, the structure is subjected to chemical
mechanical polishing to remove desired amounts of the electrically
conductive material and to result in the structure illustrated in
FIG. 1b.
FIG. 2 illustrates a typical single wafer polisher. The device
illustrated in FIG. 2 includes a platen 7. A polishing pad is
arranged on platen 7. The platen 7 may rotate as indicated by arrow
9.
A wafer 11 may be arranged in a face down position such that the
surface to be polished faces the platen 7. The wafer may also
rotate as indicated by arrow 13. FIG. 3 illustrates a
cross-sectional view of the arrangement of the platen and the
wafer.
Typically, such single wafer polishers have a low throughput. This
is at least in part due to their ability to process only one wafer
at a time. Therefore, such polishers have a low throughput. A low
throughput not only increases the cost of chemical mechanical
polishing, but also increases the cost of chemical mechanical
polishing.
Another drawback of such single wafer polishers is that they
typically utilize the same pad for all polishing operations,
regardless of the nature of the material being removed as well as
the stage of material removal. Furthermore, such polishing
apparatuses typically apply monolithic pressure. In other words,
the polishing apparatus can only apply single pressure to a
substrate as well as across all areas of the substrate.
To address the shortcomings, with respect to low throughput, of the
apparatus illustrated in FIGS. 2 and 3, multi-wafer polishers such
as that illustrated in FIG. 4 have been developed. Such polishing
apparatuses may increase throughput as compared to a single wafer
polishing apparatus by a factor of about 3 to about 4 times.
However, such apparatuses typically experience the disadvantages
described above with respect to single wafer processing apparatus.
Along these lines, multi wafer processing apparatuses also
typically utilize the same pad for polishing all wafers as well as
for all stages of polishing and apply monolithic pressure and
suffer the drawbacks of these elements.
Also, with such multi-wafer processing apparatuses, losses can be
high. For example, if one of the wafers breaks during polishing, it
could damage the other wafers. Also, if there is a problem with the
apparatus scratching a wafer, rather than effect one wafer as in
the apparatus illustrated in FIGS. 2 and 3, all of the wafers on
the apparatus illustrated in FIG. 4 would be damaged.
The apparatus illustrated in FIG. 4 includes a platen The platen
may rotate as illustrated by arrow 17. A plurality of wafers 19 are
arranged on the platen in a face down configuration. Each of the
wafers may rotate as illustrated by arrows 21.
Other disadvantages of the apparatus as illustrated in FIGS. 2-4
include that they typically utilize the same rotational speed of
the pad and/or the substrate during the entire polishing process.
Typically, such apparatuses exert about 5 pounds per square inch
pressure on a substrate. Typically, the wafer rotates about 75 RPM,
while the platen rotates at about 50 RPM.
As stated above, these apparatuses typically utilize the same pad
for all aspects of the polishing operation. Additionally, these
apparatuses also typically utilize a single slurry during the
entire processing operation. By utilizing the same pad, slurry,
rotational speed, and other parameters, such apparatuses can do
little to accommodate changing conditions as the polishing process
proceeds.
A further problem with the apparatuses illustrated in FIGS. 2-4
relates to dishing of large features. Dishing may be exacerbated by
the features and operation of these apparatuses. For example,
utilizing the same processing parameters from beginning to end of
polishing may increase dishing.
With the advent of aluminum and copper trench and via filling
technology, the chemical mechanical polishing (CMP) steps have
become one of the most critical steps in chip fabrication. This is
because of the effect of CMP on opens and shorts yield.
In addition to the impact of CMP on yield, CMP is one of the most
expensive steps at least partially on account of the low throughput
of the CMP process. For example, the throughput for an M1 metal
level may not be more than 6 wafers per hour. At higher metal
levels such as a "fat wire level", where the thickness of deposited
metal could be about 2.5 to about 3 microns, the throughput of CMP
may not exceed more than about 3 wafers per hour. Low throughput is
one factor responsible for the high cost of ownership of the CMP
step. As a result, there is a need to reduce the cost of CMP.
The present invention provides solutions to the above described as
well as other problems by providing an apparatus for
electro-chemical-mechanical polishing. The apparatus includes at
least one polishing cell including a plurality of elements for
varying polishing process parameters. The present invention helps
to increase the throughput of chemical mechanical polishing tools
thereby reducing the cost of the chemical mechanical polishing
process. The present invention may also include a plurality of
polishing cells including a first polishing cell for beginning a
polishing process and a second polishing cell for completing the
polishing process.
Advantages of the present invention can include higher throughput
as compared to known CMP and/or electrochemical processors. Also,
the throughput may be independent of the thickness of the material
being removed. In particular, the present invention can increase
throughput as compared to known chemical mechanical polishing
apparatuses by a factor of about 3 to about 10 times.
The present invention provides greatly increased flexibility by
tailoring the polishing process and apparatus to a particular
application. Among the flexible aspects of the apparatus of the
present invention are dynamic pressure application, multiple and
variable polishing pads, including pad size, dynamic slurry
formulation from aggressive to mild, edge deplating, particle
cleaning, such as in a recycling loop and rework rotate to enhance
yield.
In particular, the present invention can adapt to the
characteristics of the material being removed to result in a custom
polishing of each individual substrate. This is particularly
important where there is poor uniformity of deposited material.
Along these lines, the present invention can include multiple
polishing pads. The polishing pads can have different
characteristics to conform to the desired material removal. By
utilizes different polishing heads with different polishing pads
the present invention can optimize polishing rates.
Also along these lines, the present invention may include a dynamic
slurry formulator for formulating various slurry compositions to
customize the slurry to a particular application. To help
accomplish this, the present invention can in situ mix slurries
with oxygen and nitrogen injection to control the finishing
corrosion of polishing surfaces. Also, the present invention may
include means for injecting O.sub.2, CO.sub.2, N.sub.2, into
slurry. Custom formulating slurries can help ensure that the
present invention tailors the polishing to particular
substrates.
To further adapt the polishing process to the substrate and the
material, the present invention may also include a monitor for
continuously monitoring residual metal. Along these lines, the
present invention can include an adaptive feedback loop for varying
pressure, slurry type, temperature, slurry quench, as well as other
characteristics of the polishing process. This helps to make the
present invention a dynamic polisher.
Also, the present invention can eliminate residual metal at a wafer
edge. Along these lines, the present invention may also include a
wafer edge deplater to remove deposits in the vicinity of the edges
of a wafer.
The present invention may also be utilized for dynamic copper
surface passivation. For this purpose, CO.sub.2, N.sub.2,
(NH.sub.4).sub.2, CO.sub.2, among other materials may be
utilized.
The present invention may also help to eliminate dishing and large
features. The present invention accomplishes this through the
multiple heads, variable pressure, and other aspects of the
invention discussed herein that can tailor the polishing
process.
Embodiments of the present invention, discussed below in greater
detail, can provide, among other features fast wafer
preplanarization thickness and uniformity profiling or mapping to
determine optimum processing steps. The present invention may also
cooperatively and dynamically detect polishing end points. The
present invention can include a separate electroetching head with
segmented cathodes for accelerated metal removal. The present
invention can also include a fast planarized metal surface
comparator mapping station with a dynamic feedback loop. The
present invention can also include a yield recovery loop to remove
materials from slurries and electroetching solutions.
Utilizing the above and other attributes, the present invention can
tailor the polishing process to the thickness and uniformity of
material on a wafer to minimize planarization time and optimize
yield. The present invention may include one or a plurality of
chambers for carrying one or more of the above steps. For example,
certain aspects of characterization of the material in polishing
may take place in one chamber and certain aspects of the
characterization of the material being removed and being polishing
may take place in the other chamber or chambers. The present
invention can also include a single processing chamber or cell that
includes means for varying the polishing process.
FIG. 5 illustrates an embodiment of an apparatus according to the
present invention. The apparatus illustrated in FIG. 5 includes two
processing chambers 23 and 25. Processing chamber 23 may include an
input opening 27 for receiving substrates, such as semiconductor
wafers, for processing in the chamber. Once received in chamber 23,
a substrate 29 may be arranged on a substrate support illustrated
in FIG. 6 and described below in greater detail. Typically,
according to the present invention, a wafer being processed faces
up as opposed to facing down such as in the apparatuses illustrated
in FIGS. 2-4. As represented by arrow 31, a substrate 29 in the
processing chamber may rotate.
Upon entering a chamber, material on a substrate may be
characterized. Along these lines, the present invention may include
etching and profiling elements in processing head 33. Processing
head 33 may include a plurality of tools 35 for removing material
from a substrate as well as characterizing the material from the
substrate. The head 33 may be arranged over the substrate 29 to be
polished in order to sense and process the substrate.
Along these lines, head 33 may be arranged at the end of apparatus
for altering the position of the head 33. So that it may move from
the position illustrated in FIG. 5 to a position over the substrate
29. According to some embodiments, head 33 as well as other heads
including other polishing and sensing apparatuses may be arranged
on a single support that may alter their position so that they may
alternately be positioned over or remotely from the substrate 29 in
the position illustrated in FIG. 5. According to another
embodiment, a single apparatus may alternately engage and alter the
position of the various sensing and processing heads but only be
engaged to one sensing and/or processing head at a time, returning
each processing and/or sensing head to its original position after
sensing and/or processing a substrate.
Processing chamber 23 may also include a polishing tool head 37.
Head 37 may include a plurality of polishing pads 39. The head 37
may be a rotating turret as described below. The head 37 may be
arranged over the substrate to act on the substrate, such as to
polish the substrate. According to one embodiment, one of the pads
could be lowered to a lower level than the others. The turret could
then be arranged over the substrate and the lowered pad could act
on the substrate.
Polishing slurries may be formulated in a dynamic slurry formulator
41. The slurries may be fed to polishing head 43 which may
alternately also be arranged over the substrate 29.
In the apparatus such as that illustrated in FIG. 5, processing
chamber 23 may be characterized as a planarization chamber. In this
chamber, an uneven surface of material on a substrate 29 may be
planarized. According to such a process, the material, including
its thickness and uniformity may be detected by, for example, head
33. Along these lines, head 33 may include one or more sensors.
Such sensors can include non-contact eddy current based sensors
known in the art.
After detecting the material, the material may be removed utilizing
various chemical mechanical polishing and electroetching elements
of the processing heads 33, 39, and 43 illustrated in chamber 23 of
the apparatus shown in FIG. 5. Along these lines, to accomplish the
polishing, various slurries may be formulated and utilized in the
polishing process.
After being processed in chamber 23, a substrate 29 may be moved to
chamber 25. When arranged in chamber 25, substrate 29 may also
rotate as illustrated again by arrow 31. Processing chamber 25 may
include a processing head 45. Processing head 45 may include one or
more brush tools 47. The embodiment illustrated in FIG. 5 includes
four brush tools on processing head 45. The brush tools may be
utilized to help remove material from the substrate 29. Brush tools
may provide a finer polishing dynamic chemical mechanical polishing
tool.
Processing chamber 25 may also include a particle cleaning and
surface passivation system 49 for helping to remove particles from
the surface of substrate 29 as well as passivating the surface of
substrate 29. Particle cleaning and surface passivation may take
place after or before utilization of brush tools 47.
At least one surface comparator 51 may be included in processing
chamber 25 for scanning the surface of substrate 29 before, during
and after processing of the substrate to help determine the
condition of the surface and whether the surface requires further
processing. Such comparators are known in the art and one of
ordinary skill in the art could determine an appropriate device to
utilize in this context. One or more of the surface comparators
could be arranged over a substrate being processed to sense the
substrate.
Processing chamber 25 may include processing head 53. In the
present invention, the head 53 may include additional processing
tools. Typically, head 53 is a polishing head such as that
illustrated in FIGS. 6a and 6b and described in greater detail
below.
After processing in chamber 25, wafers may exit the system through
output 55.
FIG. 6 represents a cross-sectional view of a processing head that
may be included in one of the processing chambers 20-25 shown in
FIG. 5.
FIG. 6a represents a cross-sectional view of an embodiment of an
apparatus according to the present invention.
FIG. 6a illustrates an embodiment of a device according to the
present invention. The embodiment illustrated in FIG. 6a may be
utilized for carrying out both chemical mechanical polishing and
electroetching of a substrate. Along these lines, the embodiment
illustrated in FIG. 6a includes a polishing head 201 for carrying
chemical mechanical polishing on a substrate 203. The polishing
head may include a pad region illustrated in FIG. 6b and discussed
below in greater detail.
The apparatus illustrated in FIG. 6a also includes an anode 203 and
cathode 205 for electroetching material from the substrate. The
cathode 205 may be arranged adjacent the polishing head while the
anode 207 typically the workpiece, may be provided in contact with
the rotating platen 209. Or the substrate may simply form the
cathode. The present invention may include a power supply for
supplying power to the anode or workpiece and the cathode.
The substrate 203 or the anode may be supported on substrate
support 209. The workpiece 203 may be energized to serve as an
anode. To enhance the evenness and speed of the chemical mechanical
polishing and other processes, the substrate support 209 may rotate
as indicated by arrow 211.
As stated above, the present invention may also include elements
for carrying out chemical mechanical polishing. These elements can
include a polishing head. FIG. 6a illustrates an embodiment of a
polishing head 201. As indicated by arrows 213 and 215, the
polishing head may be rotated as well as having its position
altered in a lateral direction. Also, position of the head may be
vertically altered, to move away from the substrate or downward to
increase polishing pressure on the workpiece.
While the polishing head and/or the substrate support may both
rotate, it is not necessary that either rotate. Also, while the
substrate support rotates, the head 201 may transverse laterally as
during etching operations. Lateral movement of the head may also
take place without the substrate rotating.
Polishing slurry may be introduced between the polishing head and
the substrate to be polished through at least one slurry
introduction orifice or port 217 provided on the polishing head.
The at least one slurry port 217 may be connected to a supply of
polishing slurry 218 as discussed in greater detail below.
FIG. 6b illustrates a front view of the polishing head illustrated
in cross-sectional view in FIG. 6a. The embodiment of the polishing
head illustrated in FIG. 6b includes a pad region 219. The pad
region includes surfaces that will actually engage the surface of
the substrate being polished.
To enhance distribution of slurry throughout the region between the
polishing head and the substrate, the polishing head may include at
least one slurry distribution gap or runner 221. The embodiment
illustrated in FIG. 6b includes a plurality of slurry distribution
gaps or channels.
To enhance the distribution of slurry further, the slurry
distribution gap(s) may have a shape to encourage the slurry(ies)
to be distributed throughout the space between the polishing head
and the substrate. The embodiment of the slurry distribution gap
illustrated in FIG. 6b includes a curved shape that radiates in a
curve away from a central region of the polishing head. FIG. 6b
also illustrates the slurry introduction port 217.
FIG. 6b also illustrates the cathode 205 illustrated in
cross-section in FIG. 6a. As illustrated in FIGS. 6a and 6b, the
cathode may be arranged in the vicinity of and/or adjacent the
polishing head 201. As illustrated in FIGS. 6a and 6b, the cathode
may be arranged adjacent a side wall of the polishing head.
As illustrated in FIG. 6b, the cathode 205 may include a surface
223 having a shape complimentary to the contour of the shape of the
side wall of the polishing head 201. Including a cathode having a
complimentary shape to the exterior surface of the side wall of the
polishing head can help to increase the surface area contact
between the cathode and the polishing head where the cathode
contacts the polishing head. As illustrated in FIG. 6b, the entire
cathode 205 may have a shape complimentary to the shape of the side
wall of the polishing head 201.
Also, the cathode may be removable. Whether removable or not, the
cathode may be located about 2 to 3 mm from the walls of the
polishing head. An easily detachable cathode may be fabricated from
stainless steel or titanium or other suitable materials. As seen in
FIG. 6b, the cathode may include inlets 205b and 205c for at least
one etching or polishing solution. The cathode may also include
channel 205d for outlet or discharge of the etching or
electropolishing solution on the workpiece 203.
For electrolyte etching or polishing operations, the electrolyte or
electrolytes may be pumped through the inlets 205b and 205c, shown
in FIG. 6a, of the cathode at a flow rate of about 0.5 liters per
minute to about 10 liters per minute. As the electrolyte(s)
flow(s), the cathode material 205f, illustrated in FIG. 6b, may be
rendered cathodic, with voltage that may range between about 1 volt
and about 10 volts. Along these lines, the cathode assembly may
include an electrical connection 205g to a power supply.
The cathode assembly may include a dam wall 205e, shown in FIG. 6b.
The dam wall may help maintain a liquid gap of about 1 mm to about
5 mm between the cathode material 205f and the workpiece 203. Also,
the dam wall may be fabricated from an insulating material. One
example of an insulating material that may be utilized in the dam
wall 205e is high density polypropylene. Of course, any suitable
insulating material may be utilized in the dam wall.
The dam wall 205e may also act as a wave guide. As such, the dam
wall 205e may direct the electric field to the workpiece. The dam
wall 205e may also shield the workpiece region not immediately
below the cathode material 205f from dissolution.
During the electroetching or polishing step, the substrate holder
209 may rotate the workpiece 203 at a rate of about 205 revolutions
per minute to about 50 revolutions per minute. Also during the
electroetching or polishing step, the head 201 may move laterally
across the workpiece at a speed that may range between about 0.3
centimeters per second to about 3 centimeters per second.
The present invention may include a sensor 225 for measuring the
amount of material removed or left on the workpiece by the scanning
cathode 205, as the cathode travels across the workpiece. The rate
of material removal from the workpiece may range from about 0.05
microns per second to about 1.5 microns per second.
After the material removal operation, the workpiece may momentarily
rinsed with deionized water (DI). The DI may be pumped through
inlet 205c of the cathode assembly. The time for this brief rinse
cycle may range between about 2 seconds to about 5 seconds. During
the rinse, the substrate may be rotated at a rate of about 60 rpm
to about 300 rpm. During the rinse cycle, the head 201 may retract
upwards away from the workpiece about 2 cm to about 5 cm.
After the rinse step, if included, the chemical mechanical
planarization (CMP) of the remain metal on the workpiece 203 may be
initiated. If no rinse is carried out, the CMP may be carried out
after the electroetch.
Also arranged adjacent to the polishing head 201 may be at least
one sensor 225. The sensor(s) may vary, depending upon the
processes carried out. For processing metals, an eddy current probe
may be used to measure the amount of metal left on the workpiece.
For insulator polishing, an ellipsometric sensor may be used to
measure the amount of insulator left on the workpiece.
Another example of a sensor utilizes a UV visible fiber optic array
to detect the presence of certain reaction compounds or by
products. By detecting these materials, the sensor may detect end
points during CMP operations. A UV sensor may be utilized in a
reflector mode to detect various materials since UV light typically
is reflected differently by different materials, and particularly
different metals.
Further arranged adjacent to the polishing head may be at least one
second sensor 227 to detect a polishing end point. For example, the
end point detector could be an electrochemical sensor calibrated to
detect the transition of one type of material to another. For
example, the at least one sensor could include a pH sensor. Such a
sensor could detect changing conditions as a change occurs from one
chemical reaction to another.
Typically, sensor 225 and 227 operate in a collaborative manner.
For instance, sensor 225 may initially quickly measure the
thickness and profile of material such as metal deposited on the
workpiece. From this information, the sensor may select the optimum
recipe of electropolishing and/or CMP processes required.
After electropolishing and/or CMP processes are initiated, toward a
later part of the CMP process, sensor 225 may activate sensor 227.
With both sensors activated, they may both work in a collaborative
manner. For example, in the polishing of copper films with a
tantalum barrier layer in a damascene type structure, sensor 225
may control the initial portions of Cu electroetching and CMP
overburden removal. As the amount of metal left, for example, is
reduced to about 50 nm to about 100 nm, sensor 227 may be
activated. A higher sensitivity of sensor 227 may enhance endpoint
detection, on the titanium barrier layer, while sensor 225 may
measure the thickness of the barrier material needed to be
removed.
Sensor 225 may initiate an appropriate choice of recipe for barrier
removal and may activate flow of barrier slurry through inlet 205c.
On the other hand, sensor 227 may determine titanium barrier
endpoint and may initiate a rinse recipe. The rinse could be
initiated to clean off all slurry from the workpiece. The rinse
could be pumped through chamber 218. The workpiece may then be spun
dry and unloaded.
As stated above, at least one slurry may be introduced through at
least one slurry port 217. The slurry(ies) may be contained in at
least one slurry reservoir 218 or be fed into slurry reservoir from
slurry sources. The slurry reservoir 218 may be connected to slurry
port 217 through slurry conduit 229. The embodiment illustrated in
FIG. 6a includes two slurry sources 231 and 233 for introducing two
different slurries into slurry reservoir 218.
To enhance the action of the slurries in the chemical mechanical
polishing, nitrogen and/or oxygen, ammonia or CO.sub.2 may be
introduced into the slurry(ies). Oxygen and nitrogen may effect the
polishing rate as well as the degree of smoothness of the
polishing. The nitrogen and/or oxygen may be introduced into the
slurry(ies) at any point prior to introduction of the slurry(ies)
into slurry reservoir 219 or introduction into the space between
the polishing head and the substrate.
Accordingly, the present invention may include a source of nitrogen
235 and a source of oxygen 237. The nitrogen may be in the form of
N.sub.2, while the oxygen may be in the form of O.sub.2. The oxygen
may also be introduced in the form of inorganic or organic
peroxides or iodates. Any source of nitrogen or oxygen may be
utilized, including any nitrogen or oxygen containing compound.
For example, to generate a move aggressive slurry, oxygen may be
introduced into chamber 218. The oxygen flow rate may range from
about 5 sccm/L of slurry to about 100 sccm/L of slurry in the
slurry mix chamber 218.
For some metals, the metal removed rate may be higher when the
metal is oxidized. For example, nitric acid could be utilized to
oxidize the metal. The introduction of higher concentration of
oxygen into the slurry may enhance metal removed rate. However,
this enhanced removed rate, while highly beneficial when there is
large metal overburden, could produce disastrous results with
respect to metal removal endpoint. This is because the material
insides the trenches and vias may be removed where such removal is
not desired.
Prior to the endpoint of metal removal, N.sub.2 may be sequentially
introduced into the slurry to displace the more aggressive oxygen
introduced earlier in the process. The presence of N.sub.2 in the
slurry may reduce the aggressiveness of the slurry and help
produced a highly smooth and reflective finish on the end product.
The flow rate of N.sub.2 may range between about 10 sccm/L of
slurry to about 500 sccm/L of slurry in chamber 218.
Also, chamber 218 may be equipped with flow control values to
control slurry delivery through channel 217. Additionally, chamber
218 may include a coarse filter for filtering particles having
dimensions of about 1 to about 30 microns to remove undesirable
particles from the slurry.
In some slurry systems, sensor 227 may detect pH changes. The pH
may change during the CMP process. The pH change typically is due
to by-products of the reactions taking place. The change in pH may
degrade the polishing rate and the nature of the finish on the end
product. For such systems, the introduction of CO.sub.2 or NH.sub.3
gas may be used to control the pH in situ on the polishing pad. The
flow rate of CO.sub.2 may range between about 3 sccm/L of slurry to
about 20 sccm/L of slurry.
The judicious combination of O.sub.2, N.sub.2, CO.sub.2, NH.sub.3
and/or other gases may be used to enhance the polishing of Cu, Al,
W, Ta, Ti, TiN, Cr, Au, Ag, Ni, SiO.sub.2, SiN, SiO.sub.x N.sub.y,
amorphous metal, ferromagnetic films, such as parmalloy, high
dielectric constant materials, such as with a dielectric constant
greater than about 9, and lower dielectric constant materials, such
as with dielectric constant lower than about 3 to about 5.
The slurries may be formulated to carry out the CMP at various
rates. The in situ slurry formulation could be carried out to
process at a slow rate, medium rate, and fast rate, sequentially or
in any desirable combination.
The present invention may utilize a dynamic loop for controlling
formulation of the slurry(ies) and control of the polishing
process. The dynamic control loop is an alternative to manually
controlling the polishing slurry formulation and polishing process.
The various sensors described herein may be utilized to sense
slurry conditions as well as condition of the substrate and stage
of material removal. The sensors may act cooperatively to control
the process. The sensors may also act adaptively, for control of
the process without an operator. The control loop and utilization
of the sensors may apply to the electroetching process as well.
In addition, the chamber 218 may contains heating elements to help
maintain the formulation slurry at optimum temperature to prevent
particulate agglomeration.
As stated above, the present invention also provides a method for
removing material from a substrate. The method includes introducing
a substrate into an apparatus such as that described above.
Chemical mechanical polishing is performed on the substrate and
electroetching is performed on the substrate without transferring
the substrate to another apparatus.
One of shortcoming of traditional methods of polishing wafers is
that the substrate faces down on a pad. Enhancing slurry transport
to the substrate requires that the platen typically is several
times larger than the substrate. The slurry is typically dispensed
on the pad close to the substrate as the platen and/or the
substrate rotates. Various complicated substrate motions, such as
orbital or planetary motions, are often required to help ensure
that fresh slurry reaches the center of the substrate.
According to the present invention, the slurry may be metered
through the center of the polishing head. To further enhance fresh
slurry distribution, the pads instead of being flat and continuous
may be shaped and discontinuous. Fresh solution may be transferred
to different regions of the pad through the gaps 221, or runners,
separating the various pad elements 219.
The shaped runners may be designed for optimum slurry dispersal to
various parts of the pad. For example, the runners 221 may be wider
in the vicinity of the center of the pad and narrower in the
vicinity of the periphery of the pad. The narrowest section may
occur in the vicinity of the edge of the pad. This design may not
only enhance slurry flow and dispersal throughout the head, but it
may also maximize slurry retention times over the head. The latter
aspect may reduce amount of slurry needed to polish a given
substrate.
FIG. 6d illustrates a cross-sectional view of a portion of the
polishing head illustrated in FIG. 6a. As such, FIG. 6d illustrates
pad region 219, slurry distribution gaps 221, and slurry orifice
217, all included on polishing head 201.
The second chamber 25 may carry out a rapid inspection of substrate
29. In processing chamber 25, a barrier utilized in plating some
materials on semiconductor wafers may be removed.
For rework or yield enhancement or recovery, sites with residual
metal may be fed to the main polisher. The wafer may be transferred
back to processing chamber 23 or the residual metal may be removed
in chamber 25. A small polishing head, such as head 53 may be
utilized to remove metal residues locally. A small polishing head
may have a diameter of about 5 mm.
The device described above and shown in FIGS. 6a-6d may be utilized
in any embodiment of the present invention. A turret that includes
a plurality of polishing pads or heads could include a plurality of
the devices shown in FIGS. 6a-6d.
FIG. 7 illustrates another embodiment of a wafer processor
according to the present invention. The apparatus illustrated in
FIG. 7 includes three processing chambers 100, 102, and 104. The
polishing process may be partitioned into various stages that may
be carried in each of the polishing cells. For example, similar to
the first polishing chamber in the apparatus illustrated in FIG. 5,
the first processing chamber or cell 100 in the embodiment
illustrated in FIG. 7 may characterize metal thickness and
distribution on the substrate.
A substrate may be introduced into cell 100 through input portal
106. The substrate may be arranged on a platen 108. After
introducing a substrate into processing cell 100 and characterizing
the material on the substrate, a slurry may be formulated in slurry
formulator 110 appropriate to the characteristics of a material on
the substrate to be removed. Typically, this first polishing slurry
is formulated to rapidly eliminate metal topography and thickness
and then polish the wafer close to the barrier layer utilized in
depositing the metals and semiconductor device manufacture.
The processing cell 100 may include a head 114 including a
plurality of polishing tools 111, 112, and 113. The polishing tools
may include chemical mechanical polishing pads. The polishing pads
may have various characteristics for various degrees of polishing.
For example, the polishing pads could have characteristics for
aggressive material or removal, mild material, or any degree
therebetween.
Processing head 114 may be a rotating turret 114. The tools that
may be included in the first cell include three polishing tools
111, 112, and 113 on rotating turret 114. The tools can include a
high speed electropolishing head, a high rate polishing head, and a
variable pressure polishing head. In reality, any desired tools may
be included on the turret.
In an important point here is that each polishing cell may include
a plurality of tools, sensors, and other equipment to optimize the
polishing process to tailor it to a specific substrate and material
on a substrate. This is also the reason for including a slurry
formulator to optimize slurry composition.
The first polishing cell 100 may include head 116. Head 116 may be
similar to the head shown in FIGS. 6a and 6b as described above in
greater detail.
Additional processing steps may be carried out in processing cell
100. For example, an intermediate slurry quench and rinse step may
be carried out. This step may be brief.
After processing in cell 100, the material remaining on the
substrate may again be detected. As the substrate is transferred
from polishing cell 100 to polishing cell 102, the most recent data
regarding the material in a substrate may be transferred to the
second polishing cell. For example, the latest data regarding metal
remaining on the substrate and/or uniformity of the metal remaining
on the substrate may be transferred to the second processing
cell.
Similar to the process carried out in the first processing cell,
upon arrival of the substrate and data regarding the material in a
substrate arrives in the second polishing cell, the optimum
processing steps may be determined for treating the substrate.
Along these lines, the second processing cell may determine which
tool or tools to utilize to process the substrate. If chemical
mechanical polishing is utilized, an optimal slurry recipe may be
determined to complete the polishing process.
The second processing cell may include four polishing heads 118,
120, 122, and 124 arranged on a rotating turret. The tools can
include high rate polishing head, an intermediate rate polishing
head, a touch up finishing head, and small head polisher utilized
for localized polishing to remove metal residues.
Processing head 126 may be included in cell 102. Processing head
126 may act as the other processing heads, such as that 116, as
described above.
Depending on metal profile, during polishing, the pressure on the
wafer can be distributed. Thus, the polishing pressure can be
programmed to radially vary as the polishing head moves across the
wafer. According to one embodiment, the pressure may be varied by
differentially applying pressure to the backside of the wafer as
the polishing head moves. By controlling where the pressure is
applied to the wafer, where the wafer contacts the head, or
contacts the head with greater force, may be controlled. Typically,
such polishing includes a local polishing head that is smaller than
the wafer.
After processing in the second polishing cell 102, the substrate
may be moved to a third polishing cell 104. The third polishing
cell may include a polishing platen 130 for supporting the
substrate. Rather than including the polishing platen in each
polishing cell, the polishing platen may travel between the cells.
Along these lines, a device according to the present invention
could include a plurality of polishing platen that may be
introduced at one end of the apparatus and discharged from the
apparatus at the other end.
The third cell may include a plurality of brush tools 132, 134, and
136 arranged on a turret 138. The brush tools may be utilized for
slurry removal from the substrate. Polishing cell 104 may also
include a particle cleaning passivation tool 140. To detect the end
point of the cleaning, the third cell may include a scanning laser
holography system to provide feed back to the cleaning tools.
Polishing cell 104 may include processing head 139. The processing
head 139 may be similar to processing heads 116, as described
above.
Cell 104 also may include an output 142 where substrates may be
discharged after processing.
By including in situ dynamic slurry formulators in polishing cells
of the present invention, slurries may be formulated as desired
depending upon desired metal removal rates. New slurries may be
formulated from a plurality of master batches. Typically, three
master batches may be utilized in various combinations to formulate
the slurries.
To further vary the slurry composition, slurry formulators may
include additive meters for detecting properties of the slurries
and varying them. Along these lines, the slurry formulators may
include oxygen, nitrogen, and/or carbon dioxide injectors to supply
these materials to the slurries to vary the slurry
characteristics.
Characteristics of the slurries may be further varied by a slurry
chiller and slurry heater to control slurry temperature. Along
these lines, the present invention may include one or more slurry
heaters to control slurry temperatures for optimum metal polish.
The slurry heater may be an infrared heater. One or more slurry
chillers may be included in the present invention for polish
surface cleaning and passivation. The slurry chillers may utilize
nitrogen and carbon dioxide injection.
Devices according to the present invention can include one or more
processors for analyzing data regarding the characteristics of the
material to be removed from the substrate and determining
appropriate tools and/or slurry compositions to utilize for
removing the material.
Apparatuses according to the present invention can also vary
pressure on material being removed from the substrate during
polishing of the material. The pressure may be varied radially as a
polishing tool moves across the wafer. In addition to rotating the
substrate and/or the polishing heads or other polishing
apparatuses, the position of either one or both of these may be
laterally altered. The polishing pressure may also be varied in any
other directions in any manner that may be required or desired to
remove the material from the substrate.
In addition to including a slurry formulator for formulating and
introducing at least one slurry, the present invention may include
means for directing deionized water at a substrate. The deionized
water may be delivered through the same means as the slurries.
The at least one pattern comparer may compare a pattern of material
on a substrate with a known pattern to determine how removal of the
material should proceed.
Rather than including a plurality of polishing cells, all of the
functions carried out in the various cells in the embodiments
illustrated in FIG. 5 and FIG. 7 may be carried out in a single
polishing cell. Along these lines, the present invention may
include at least one polishing cell including a plurality of
elements for varying polishing process parameters. The parameters
may include polishing pressure, slurry composition, polishing pad
type, etch current, as well as other parameters.
The present invention also includes a method of removing material
from a substrate. The method includes arranging a substrate on an
apparatus such as that described above, detecting material from the
substrate forming a first polish operation and completing the
polish operation. The method includes varying various parameters of
the polishing operation, such as slurry composition, polishing pad
pressure, polishing pad characteristics, electroetch current and/or
any other process parameter. The present invention also includes
detecting points where the polishing should be terminated such as
detecting an end point of the polishing operation. Formulating the
slurry may also include introducing at least one of oxygen, carbon
dioxide, and nitrogen into the polishing slurry.
The foregoing description of the invention illustrates and
describes the present invention. Additionally, the disclosure shows
and describes only the preferred embodiments of the invention, but
as aforementioned, it is to be understood that the invention is
capable of use in various other combinations, modifications, and
environments and is capable of changes or modifications within the
scope of the inventive concept as expressed herein, commensurate
with the above teachings, and/or the skill or knowledge of the
relevant art. The embodiments described hereinabove are further
intended to explain best modes known of practicing the invention
and to enable others skilled in the art to utilize the invention in
such, or other, embodiments and with the various modifications
required by the particular applications or uses of the invention.
Accordingly, the description is not intended to limit the invention
to the form disclosed herein. Also, it is intended that the
appended claims be construed to include alternative
embodiments.
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